Electrical contact device and method of preparation thereof

ABSTRACT

An electrical contact device having an electrical conductivity of at least 57% based on the International Annealed Copper Standard and unexpected properties of increased thermal stability, ultimate elongation, bendability, ductility, creep resistance, tensile and yield strength, and fatigue resistance when compared to conventional aluminum alloy connectors. The electrical contact device contains substantially evenly distributed iron aluminate inclusions in a concentration produced by the addition of more than about 0.20 weight percent iron to an alloy mass containing less than about 99.78 weight percent aluminum, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0002 to about 0.20 weight percent copper, and up to about 0.15 weight percent conventional impurities normally found within a commercial aluminum alloy. The substantially evenly distributed iron aluminate inclusion are obtained by casting an alloy consisting essentially of less than about 99.78 weight percent aluminum, more than about 0.20 weight percent iron, from about 0.07 to about 0.35 weight percent magnesium, from about 0.01 to about 0.25 weight percent silicon, from about 0.0003 to about 0.20 weight percent copper, and up to about 0.15 weight percent typical impurities to form an aluminum alloy bar, billet, or shape, subsequently forming into a contact device without intermediate anneals and annealing the formed contact device. After annealing, the contact device has the aforementioned novel and unexpected properties of increased thermal stability, ultimate elongation, tensile strength, electrical conductivity of at least 57% of the International Annealed Copper Standard, and increased bendability, fatigue resistance, creep resistance, ductility, and high yield strength.

United States Patent [191 Chia et al.

[4 Oct. 21, 1975 1 1 ELECTRICAL CONTACT DEVICE AND METHOD OF PREPARATIONTHEREOF [75] Inventors: Enrique Chia; Herbert M. Hanegan;

Paul S. Keith, all of Carrollton, Ga.

[73] Assignee: Southwire Company, Carrollton,

22 Filed: Nov. 19, 1973 21 Appl. No.: 417,177

Related US. Application Data [63] Continuation-impart of Ser. No.200,576, Nov. 19,

1971, abandoned.

[52] US. Cl 339/278 C; 29/193; 29/527.7; 29/630 C; 75/138; 148/2 [51]Int. Cl. H01R 3/02 [58] Field of Search... 29/193, 630 C, 527.5, 527.7;75/138; 148/2, 32; 164/76, 57; 339/278 C OTHER PUBLICATIONS R. H.Harrington, The Effects of Single Addition Metals on theRecrystallization, Electrical Conductivity and Rupture Strength of PureAluminum, Transactions of the American Society for Metals, Vol. 41, pp.443-459, 1949.

Primary ExaminerC. W. Lanham Assistant ExaminerV. K. Rising Attorney,Agent, or FirmVan C. Wilks; Herbert M. Hanegan; Stanley L. Tate [57]ABSTRACT An electrical contact device having an electrical conductivityof at least 57% based on the International Annealed Copper Standard andunexpected properties of increased thermal stability, ultimateelongation, bendability, ductility, creep resistance, tensile and yieldstrength, and fatigue resistance when compared to conventional aluminumalloy connectors. The electrical contact device contains substantiallyevenly distributed iron aluminate inclusions in a concentration producedby the addition of more than about 0.20 weight percent iron to an alloymass containing less than about 99.78 weight percent aluminum, fromabout 0.07 to about 0.35 weight percent magnesium, from about 0.01 toabout 0.25 weight percent silicon, from about 0.0002 to about 0.20weight percent copper, and up to about 0.15 weight percent conventionalimpurities normally found within a commercial aluminum alloy. Thesubstantially evenly distributed iron aluminate inclusion are obtainedby casting an alloy consisting essentially of less than about 99.78weight percent aluminum, more than about 0.20 weight percent iron, fromabout 0.07 to about 0.35 weight percent magnesium, from about 0.01 toabout 0.25 weight percent silicon, from about 0.0003 to about 0.20weight percent copper, and up to about 0.15 weight percent typicalimpurities to form an aluminum alloy bar, billet, or shape, subsequentlyforming into a contact device without intermediate anneals and annealingthe formed contact device. After annealing, the contact device has theaforementioned novel and unexpected properties of increased thermalstability, ultimate elongation, tensile strength, electricalconductivity of at least 57% of the International Annealed CopperStandard, and increased bendability, fatigue resistance, creepresistance, ductility, and high yield strength.

26 Claims, 5 Drawing Figures US. Patent Oct. 21, 1975 ELECTRICAL CONTACTDEVICE AND METHOD OF PREPARATION THEREOF CROSS REFERENCE TO RELATEDAPPLICATIONS This application is a continuation-in-part of copendingapplication Ser. No. 200,576, filed Nov. [9, 1971 now abandoned.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagramatic representationof one embodiment of the present invention illustrating a Butt Splice.

FIG. 2 is a diagramatic representation of the present invention embodiedas a Stacking Pin.

FIG. 3 is a diagramatic representation of the present invention embodiedas a Ring Tongue Terminal.

FIG. 4 is a diagramatic representation of the present invention embodiedas a Flanged Spade Terminal.

FIG. 5 is a diagramatic representation of the present invention embodiedas a Rectangular Blank Tongue Terminal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention relates to anelectrical contact device suitable for use as an electrical conductorand more particularly concerns an electrical contact device having anacceptable electrical conductivity and improved thermal stability,elongation, bendability, and tensile strength.

Contact devices as used herein are understood to include single andmultiple circuit connectors, tubes, bus bars, ferrules, fasteners,terminals, splices, receptacles, pins, tabs, sockets, jacks, plugs, andother like contact devices for conducting electricity.

The use of various aluminum alloys as conductors of electricity is wellestablished in the art'. Such alloys characteristically haveconductivities of at least 57% of the International Annealed CopperStandard (hereinafter sometimes referred to as IACS) and chemicalconstituents consisting of a substantial amount of pure aluminum andsmall amounts of conventional impurities such as silicon, vanadium,iron, copper, manganese, magnesium, zinc, boron and titanium. Thephysical properties of prior electrical contact devices have proven lessthan desirable, i.e., their thermal stability has rendered such contactdevices generally unsuitable for many applications. Generally desirablepercent elongations have been obtained only at less than desirablepercent elongations. In addition, the bendability, ductility, creepresistance, and fatique resistance of prior aluminum alloy contactdevices have been so low that they have been generally unsuitable formany oth erwise desirable applications.

Thus, it becomes apparent that a need has arisen within the industry foran electrically conductive contact device suitable for use with aluminumconductors which has both improved thermal stability, improved percentelongation and tensile strength, and also possesses the ability towithstand numerous bends at one point and to resist fatiguing duringuse. Therefore, it is an object of the present invention to provide anelectrical conductor device of acceptable conductivity and improvedphysical properties and suitable for use with aluminum conductors suchthat said conductors may be used in new applications. Another object ofthe present invention is to provide an electrical contact device havingnovel properties of increased thermal stability ultimate elongation andtensile strength, improved bendability, ductility, creep resistance,yield strength and fatigue resistance, and acceptable electricalconductivity. These and other objects, features and advantages of thepresent invention will become apparent to those skilled in the art froma consideration of the following detailed description of the followingdetailed description of the invention.

In accordance with this invention, the present electrically conductivecontact device is prepared from an alloy comprising less than about99.78 weight percent aluminum, more than about 0.02 weight percent iron,from about 0.07 to about 0.35 weight percent magnesium, from about 0.0]to about 0.25 weight percent copper, and up to about 0.15 weightconventional impurities normally found in a commercial aluminum alloy.

Preferably, the aluminum content of the present alloy comprises fromabout 97.25 to about 99.72 weight percent, with particularly superiorresults being achieved when from about 97.90 to about 99.35 weightpercent aluminum is employed.

The iromgontent of the present alloy advantageously comprises l fi o'mabout 0.02 weight percent to about 2.00 weighti percent, withparticularly superior results being achieved when from about 0.05 weightpercent to about Weight percent iron is employed.

Preferably from about 0.20 to about 0.15 weight percent silicon isemployed in the present alloy, with particularly superior results beingachieved when from about 0.04 to about 0.10 weight percent silicon isemployed.

The magnesium content of the present alloy advantageously comprises fromabout 0.07 to about 0.25 weight percent, with particularly superiorresults being achieved when from about 0.10 to about 0.20 weight percentmagnesium is employed.

Preferably the copper content of the present alloy comprises from about0.005 to 0.15 weight percent, with particularly superior results beingachieved when from about 0.01 to about 0.10 weight percent copper isemployed.

The present electrical contact device is prepared by initially meltingand alloying aluminum with the necessary amount of iron, magnesium,copper, or other constituents to provide the requisite alloy forprocessing. Typical impurities or trace elements are also present withinthe melt, but only. in trace quantities, such as less than about 0.05weight percent each with a total content of trace impurities generallynot exceeding about 0.15 weight percent. Preferably the individual traceelements are present in an amount of from about 0.0004 about 0.04, andthe total content of trace elements are present in an amount of fromabout 0.002 to about 0.l0 weight percent. Of course, when adjusting theamount of trace elements due consideration must be given to theconductivity of the final alloy since some trace elements affectconductivity more severely than others. Typical trace elements includevanadium, manganese and zinc.

Magnesium, iron, and copper are the major constituents added to the meltto produce the alloy of the present invention. Normally about 0.10weight percent magnesium, about 0.01 weight percent copper, and about0.50 weight percent iron are added to the typical aluminum conponentused to prepare the present alloy.

Of course, the scope of the present invention includes the addition ofmore or less magnesium, iron, and copper together with the adjustment ofthe content of all alloying constituents.

After alloying, the melted aluminum composition can be continuously castinto a continuous bar or conventionally cast into a bar, billet orshape. Where the alloy is continuously cast the bar is'hot-worked insubstantially that condition in which it is received from the castingmachine. A typical hot-working operation comprises rolling the bar in arolling mill substantially immediately after being cast into a bar.

One example of a continuous casting and rolling operation capable ofproducing continuous rod as specified in this application is as follows:

A continuous casting machine serves as a means for solidifying themolten aluminum alloy metal to provide a cast bar that is conveyed insubstantially the condition in which it solidified from the'continuouscasting machine to the rolling mill, which serves as a means forhot-forming the cast bar into rod or another hotformed product in amanner which impartssubstantial movement to the cast bar along aplurality of angularly disposed axes.

The continuous casting machine is of conventional casting wheel typehaving a casting wheel with a casting groove partially closed by anendless belt supported by the casting wheel and an idler pulley. Thecasting wheel and the endless belt cooperate to provide a mold into oneend of which molten metal is poured to solidify and from the other endof which the cast bar is emitted in substantially that condition inwhich it solidified.

The rolling mill is of conventional type having a plurality of rollstands arranged to hot-form the cast bar by a series of deformations.The continuous casting machine and the rolling mill are positionedrelative to each other so that the cast bar enters the rolling millsubstantially immediately after solidification and in substantially thatcondition in which it solidified. In this condition, the cast bar is ata hot-forming temperature within the range of temperatures, forhot-forming the cast bar at the initiation of hot-forming withoutheating between the casting machine and the rolling mill. In the eventthat it is desired to closely control the hotforming temperature of thecast bar within the conventional range of hot-forming temperatures,means for adjusting the temperature of the cast bar may be placedbetween the continuous casting machine and the rolling mill withoutdeparting from the inventive concept disclosed herein.

The roll stands each include a plurality of'rolls which engage the castbar. The rolls of each roll stand may be two or more in number andarrange diametrically opposite from one another or arranged at equallyspaced.

positions about the axis of movement of the cast bar through the rollingmill. The rolls of each roll stand of the rolling mill are rotated at apredetermined speed by a power means such as one or more electric motorsand the casting wheel is rotated at a speed generally determined by itsoperating characteristics. The rolling mill serves to hot-form the castbar into a rod of a crosssectional area substantially less than that ofthe cast bar as it enters the rolling mill.

The peripheral surfaces of the rolls of adjacent roll stands in therolling mill change in configuration; that is, the cast bar is engagedby the rolls of successive roll stands with surfaces of varyingconfiguration and from different directions. This varying surfaceengagement of the cast bar in the roll stands functions to knead orshape the metal in the cast bar in such a manner that it is worked ateach roll stand and also to simultar neously reduce and change thecross-sectional area of the cast bar into that of the rod.

As each roll stand engages the cast bar, it is desirable that the castbar be received with sufficient volume per unit of time at the rollstand for the cast bar to generally fill the space defined by the rollsof the roll stand so. I

that the rolls will be effective to work the metal in the cast bar.However, it is also desirable that the space defined by the rolls ofeach roll stand not be overfilled so that the cast bar will not beforced into the gaps be-- tween the rolls. Thus, it is desirable thatthe rod be fed toward each roll stand at a volume per unit of time 1which is sufficient to fill, but not overfill, the space defined by therolls of the roll stand.

As the cast bar is received from the continuous casting machine, itusually has one large flat surface corresponding to the surface of theendless band and inwardly tapered side surfaces corresponding to. 'theshape of the groove in the casting wheel. As the cast bar is compressedby the rolls of the roll stands, the cast bar is deformed so that itgenerally takes the crosssectional shape defined by the adjacentperipheries. of the rolls of each roll stand.

Thus, it will be understood that with this apparatus, cast aluminumalloy rod of an infinite number of different lengths is prepared bysimultaneous casting of the molten aluminum alloy and hot-forming orrolling the. cast aluminum bar. t

The continuous rod produced by continuous casting and rolling can be hotforged into an electrical contact device of required size and shape, orcan be cold forged into the required size and shape and, if desired, an-

nealed. It also can be impact extruded, extruded through dies into tubeform, cold drawn or coldforged into the required size and shape and, ifdesired, annealed.

The conventionally cast bar, billet, or shape can be impact extruded,extruded through dies into tube form,

cold drawn or cold forged into the required size and shape, and ifdesired, annealed. It can also be pierced and the pierced portion eithercold forged into the required size and shape, or extruded through diesinto tube form, cold drawn or cold forged intothe required size andshape and, if desired, annealed.

The continuously cast and continuously rolled rod and the conventionallycast baror billet can be cold or I hot rolled into a sheet. The sheetthen can be stamped,

punched, or cut and formed into the required shape about 1/l0,000 of aminute. Generally, howevencontinuous annealing temperatures and timesmay be adjusted to meet the requirements of the particular overallprocessing operation so long as the desired connec. tor properties areachieved. In a batch annealing operation, a temperature of approximately400F to about 750F is employed with residence times of about 30 minutesto about 24 hours. As mentioned with respect to continous annealing, inbatch annealing the time and temperatures may be varied to suit theoverall process so long as the desired connector properties areobtained.

During the casting of this alloy, a substantial portion of the ironpresent in the alloy precipitates out of solution as iron aluminateintermetallic compound (FeAl Thus, after casting, the bar contains adispersion of FeAl in a supersaturated solid solution matrix. As the baror billet is rolled the FeAl particles are broken up and dispersedthroughout the matrix, inhibihiting large cell formation. When thecontact device is then formed to its final shape and size withoutintermediate anneals and aged in a final annealing operation, thethermal stability, tensile strength, elongation and bendability areincreased due to the small cell size and the additional pinning ofdislocations by preferential precipitation of FeAl on the dislocationsites.

The properties of the present electrical contact device aresignificantly affected by the size of the FeAl particles in the matrix.Coarse precipitates reduce the thermal stability, percent elongation andbendability of the contact device by enhancing nucleation and thus,formation of large cells which, in turn, lowers the recrystallizationtemperature of the connector. Fine precipitates improve the thermalstability, percent elongation, and bendability by reducing nucleationand increasing the recrystallization temperature. Grossly coarseprecipitates of FeAl cause the contact device to become brittle andgenerally unusable. For purposes of this invention it is understood thatcoarse precipitates have a particle size of below 10,000 angstrom units.The majority of FeAl particles in the present aluminum alloy have aparticle size of below 10,000 angstrom units.

Upon examination of a cold drawn contact device, it is found that theprecipitates are oriented in the direction of drawing. In addition, itis found that the precipitates can be rod-like, plate-like, or sphericalin configuration.

Other intermetallic compounds which may be formed, depending upon theconstituents of the melt and the relative concentrations of elementspresent in the alloy includethe following: Al,Cu Fe, Mg Si, FeSi), CuAlAl Fe Si FeAl 3Fe Si- Al Mn, FeAl AI Mg Cu, Al Mg Al Cu Mg- AlCuMg.

The following specific examples are intended to be illustrative of theinvention, but not limiting of the scope thereof, parts and percentagesbeing by weight unless otherwise specified.

EXAMPLE 1 A comparison between prior EC aluminum alloy contact devicesand the present aluminum alloy contact devices was provided by preparingaprior EC alloy with aluminum content of 99.73 weight percent, ironcontent of 0.18 weight percent, silicon content of 0.059 weight percent,and trace amounts of typical impurities. The present alloy was preparedwith aluminum content of 99.45 weight percent, magnesium content of 0.15weight percent, iron content of 0.45 weight percent, silicon content of0.056 weight percent, copper content of 0.05 weight percent, and traceamounts of typical impurities. Both alloys were continuously cast intocontinuous bars and hot-rolled into continuous rod in similar fashion.The alloys were then formed into size 12-10 AWG ferrule connectors andtongue type connectors. The connectors were then batch furnaceannealedat similar temperatures and for similar lengths of time. The annealedconnectors were attached to copper wires and subjected to a heat cyclingtest in which current was passed through a circuit containing foursamples; a prior EC Alloy ferrule connector, a prior EC alloy tongueconnector, a present alloy ferrule connector, and a present alloy tongueconnector. The test consisted of controlled current cycling on-offperiods. Failure was considered when the connection temperature reachesC. A minimum testing time of 10,000 hours on" period (or energized) wasused. Current cycle was five hours on controlled currenton hour off. Thecontrolled current used was 30 amperes. After 10,000 hours on period, inexcess of 50 percent failures were experienced in the prior EC alloyferrule and tongue connectors. No failures were experienced for thepresent alloy ferrule and tongue connectors. A test time of 10,000 hourson" period was considered to be equal to a minimum 7 year life actualservice.

EXAMPLES 2 THROUGH 8 The procedure of Example I was repeated using sevenaluminum alloys prepared with the varying amounts of major constituentslisted below.

No failures were experienced for ferrule and tongue connectors preparedfrom the seven alloys listed.

EXAMPLES 9 THROUGH 16 The procedures of Examples 1 through 8 wererepeated except the alloys were conventionally cast into a bar,rolledinto sheet and the ferrule and tonque connectors stamped from thesheet and cold-formed into the desired shape. In excess of 50 percentfailures were experienced in the prior EC alloy connectors after a testtime of 10,000 hours on period. No failures were experienced for thepresent alloy ferrule and tongue connectors.

While this invention has been described in detail with particularreference to preferred embodiments thereof, it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention as described hereinbefore and as defined in theappended claims.

What is claimed is:

1. An electrical contact device having a minimum conductivity of 57%IACS consisting essentially of more than about 0.02 weight percent iron,from about 0.07 to about 0.35 weight percent magnesium, from about 0.01to about 0.25 weight percent silicon, from about 0.0003 to about 0.02weight percent copper, less than about 0.05 weight percent each of traceelements selected from the group consisting of vanadium, manganese andzinc, and from about 97.25 to about 99.78

weight percent aluminum, said alloy containing no more than about 0.15total weight percent of said trace elements, said contact device havingimproved thermal stability when compared against conventional ECaluminum devices which renders said contact device capable ofwithstanding repeated current cycling over an extended period of time,without failure.

2. The electrical contact device of claim 1 consisting essentially offrom about 0.20 to about 2.00 weight percent iron, from about 0.07 toabout 0.25 weight percent magnesium, from about 0.02 to about 0.15weight percent silicon, from about 0.005 to about 0.15 weight percentcopper, and from about 97.25 to about 99.72 weight percent aluminum.

3.The electrical contact device of claim 2 consisting essentially offrom about 0.05 to about 1.50 weight percent iron, from about 0.10 toabout 0.20 weight percent magnesium, from about 0.04 to about 0.10weight percent silicon, from about 0.01 to about 0.10 weight percentcopper, and from about 97.90 to abot 99.35 weight percent aluminum.

4. The electrical contact device of claim 1 wherein the silicon contentis from about 0.02 to about 0.15 weight percent, the individual traceelement content is from about 0.0004 to about 0.04 weight percent, andthe total trace element content is from about 0.002 to about, 0.10weight percent.

5. The electrical contact device of claim 1 wherein the individual traceelement content is less than about 0.0004 percent and the total traceelement content is less than about 0.002 weight percent.

6. An electrical contact device having a minimum conductivity of 57%IACS containing substantially evenly distributed iron aluminateinclusions in a concentration produced by the presence of more thanabout 0.02 weightpercent iron in an alloy mass consisting essentially offrom about 97.25 to about 99.78 weight percent aluminum, from about 0.01to about 0.25 weight percent silicon, from about 0.07 to about 0.35weight percent magnesium, from about 0.0003 to about 0.20 weight percentcopper, less than about 0.05 weight percent each of trace elementsselected from the group consisting of vanadium, manganese, and zinc,said alloy containing no more than about 0.15 total weight percent ofsaid trace elements, said iron aluminate inclusions having a particlessize of less than 10,000 angstrom units, said contact device having im-.proved thermal stability when compared against conventional EC aluminumdevices which renders said contact device capable of withstandingrepeated current cycling over an extended period of time, withoutfailure.

7. The electrical contact device of claim 6 wherein the individual traceelement content is less than about 0.0004 weight percent, and the totaltrace element content is less than about 0.002 weight percent.

8. The electrical contact device of claim 6 wherein iron is present in aconcentration of from about 0.20 to about 2.00 weight percent, magnesiumis present in a concentration from about 0.07 to about 0.25 weightpercent, silicon is present in a concentration of from about 0.02 toabout 0.15 weight percent, copper is present in a concentration of fromabout 0.005 to about 0.15 weight percent, and aluminum is present in aconcentration of from about 97.25 to about 99.72 weight percent.

9. The electrical contact device of claim 8 wherein iron is present in aconcentration of from about 0.50 to about, 1.50 weight percent,magnesium is present in a concentration of from about.0.l0 to about 0.20weight percent, silicon is present in a concentration of from about 0.04to about 0.10 weight percent, copper is present in a concentration offrom about 0.01 to about 0.10 weight percent, and aluminum is present ina concentration of from about 97.90 to about 99.35 weight percent. 7

10. The electrical contact device of claim 6 wherein the silicon contentis from about 0.02.to about 0.15

weight percent, the individual trace element content is I from about0.0004 to about 0.04 weight percent, and

the total trace element content is from about 0.002 to about 0.10 weightpercent.

11. A process for preparing an electrical contact device having aminimum conductivity of at least 57% IACS comprising the steps of: a.Alloying from about 97.25 to about 99.78 weigh percent aluminum withmore than 0.20 weight percent iron, from about 0.07 to about 0.35 weightpercent magnesium, from about 0.01 to about 0.25

of withstanding repeated current cycling over an extended period oftime, without failure.

12. The process of claim 11 including the step of an-:

nealing or partially annealing the contact device.

13. A process for preparing an electrical contact device having aminimum conductivity of at least 57% IACS comprising the steps of:

a. Alloying from about 97.25 to about 99.78 weight percent aluminum withmore than about 0.20

weight percent iron, from about 0.07 to about 0.35

weight percent magnesium, from about 0.01 to about 0.25 weight percentsilicon, from about 0.0003 to about 0.20 weight percent copper, and

less than about 0.05 weight percent each of trace elements selected fromthe group consisting of vanadium, manganese and zinc, the total traceelement content being no more than about 0.15 weight percent of saidtrace elements:

b. Continuously casting the alloy into a continuous:

bar;

0. Continuously rolling the bar in substantially that condition in whichit was cast to form a continuous.

rod; and d. Forming the rod with no preliminary or intermediate annealsinto a contact device, said contact device having improved thermalstability when compared against conventional EC aluminum devices whichrenders said contact device capable of withstanding repeated currentcycling over an extended period of time, without failure.

14. The process of caim 13 wherein the individual trace element contentis less than about 0.0004 weight percent, and the total trace elementcontent is less than about 0.002 weight percent.

15. The process of claim 13 wherein step (a) comprises alloying fromabout 97.25 to about 99.72 weight percent aluminum, from about 0.20 toabout 2.00 weight percent iron, from about 0.07 to about 0.25 weightpercent magnesium, from about 0.02 to about 0.15 weight percent silicon,and from about 0.005 to about 0.15 weight percent copper.

16. The process of claim 15 wherein step (a) comprises alloying fromabout 97.90 to about 99.35 weight percent aluminum, from about 0.50 toabout 1.50 weight percent iron, from about 0.10 to about 0.20 weightpercent magnesium, from about 0.04 to about 0.10 weight percent silicon,and from about 0.01 to about 0.10 weight percent copper.

17. The process of claim 13 wherein the silicon content is from about0.02 to about 0.15 weight percent, the individual trace element contentis from about 0.0004 to about 0.04 weight percent, and the total traceelement content is from about 0.002 to about 0.10 weight percent.

18. The process of claim 13 including the step of annealing or partiallyannealing the contact device.

19. A process for preparing an electrical contact device having aminimum conductivity of at least 57% IACS and containing substantiallyevenly distributed iron aluminate inclusions having a particle size ofless than 10,000 angstrom units, comprising the steps of:

a. Alloying from about 97.25 to about 97.78 weight percent aluminum withmore than about 0.20 weight percent iron, from about 0.07 to about 0.35weight percent magnesium, from about 0.01 to about 0.25 weight percentsilicon, from about 00003 to about 0.20 weight percent copper, and lessthan about 0.05 weight percent each of trace elements selected from thegroup consisting of vanadium, manganese and zinc, the total traceelement content being no more than about 0.15 weight percent of saidtrace elements,

b. Continuously casting the alloy into a continuous bar;

c. Continuously rolling the bar in substantially that condition in whichit was cast to form a continuous rod; and

d. Forming the rod with no preliminary or intermediate anneals into acontact device, said contact device having improved thermal stabilitywhen compared against conventional EC aluminum de vices which renderssaid contact device capable of withstanding repeated current cyclingover an extended period of time, without failure.

20. The process of claim 19 wherein the individual trace element contentis less than about 0.0004 weight percent, and the total trace elementcontent is less than about 0.002 weight percent.

21. The process of claim 19 wherein step (a) comprises alloying fromabout 97.25 to about 99.72 weight percent aluminum, from about 0.20 toabout 2.00 weight percent iron, from about 0.07 to about 0.25 weightpercent magnesium, from about 0.02 to about 0.15 weight percent silicon,and from about 0.005 to about 0.15 weight percent copper.

22. The process of claim 21, wherein step (a) comprises alloying fromabout 97.90 to about 99.35 weight percent aluminum, from about 0.50 toabout 1.50 weight percent iron, from about 0.10 to about 0.20 weightpercent magnesium, from about 0.04 to about 0.10 weight percent silicon,and from about 0.01 to about 0.10 weight percent copper.

23. The process of claim 19 wherein the silicon content is from about0.02 to about 0.15 weight percent, the individual trace element contentis from about 0.0004 to about 0.04 weight percent, and the total traceelement is from about 0.002 to about 0.10 weight percent.

24. The process of claim 19 including the step of anealing or partiallyannealing the contact device.

25. A process for preparing an electrical contact device having aminimum conductivity of at least 57% IACS and containing substantiallyevenly distributed iron aluminate inclusions having a particle size ofless than 10,000 angstrom units comprising the steps of:

a. Alloying from about 97.25 to about 99.78 weight percent aluminum withmore than about 0.20 weight percent iron, from about 0.07 to about 0.35

weight percent magnesium, from about 0.01 to about 0.25 weight percentsilicon, from about 0.0003 to about 0.20 weight percent copper, and lessthan from about 0.0003 to about 0.20 weight percent copper, and lessthan about 0.05 weight percent each of trace elements selected from thegroup consisting of vanadium, manganese and zinc, the total traceelement content being no more than about 0.015 weight percent of saidtrace elements: Casting the alloy to form a cast bar; and

Forming the bar with no preliminary or intermediate anneals into acontact device, said contact devicehaving improved thermal stabilitywhen compared against conventional EC aluminum devices which renderssaid contact device capable of withstanding repeated current cyclingover an extended period of time, without failure.

26. The process of claim 25 including the step of annealing or partiallyannealing the contact device.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 13,914,009

DATED 3 October 21, 1975 |NVENTOR(S) I Enrique hi et a1.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 1, line 50; "percent elongations" should be -tensile strengths--Column 2, line 67; "conponent" should be --component-.

Column 3, line 53; "arrange" should be --arranged--.

Column 5, line 33; "below" should be --above-- Column 6, line 15; "on"should be -one-- Column 7, line 20; "abot" should be --about--.

Column 10, line 26; "anealing" should be --annealing-.

Signed and Scaled this Twenty-ninth Day Of March 1977 [SEAL] Arrest:

RUTH C. MASON C. MARSHALL DANN Altesn'ng Officer Commissioner ofParentsand Trademarks

1. AN ELECTRICAL CONTACT DEVICEHAVING A MINIMUM CONDUCTIVITY OF 57% IACSCONSISTING ESENTIALLY OF MOETHAN ABOUT 0.02 WEIGHT PERCENT IRON, FROMABOUT 0.07 TO ABOUT 0.35 WEIGHT PERCENT AGNESIUM, FROM ABOUT 0.01 TOABOUT 0.25 WEIGHT PER SILION, FROM ABOUT 0.0003 TO ABOUT 0.02 WEIGHTPERCENT COPPER, LESS THAN ABOUT 0.05 WEIGHT PERCENT EACH OF TRACEELEMENTS SELECTED FROM THE GROUP CONSISTING OF VANDIUM, MANGANESE ANDZINC, AND FROM ABOUT 97.25 TO ABOUT 99.78% WEIGHT PERCENT ALUMINIUM,SAID ALLOY ONTAINING NO MORE THAN ABOUT 0.15 TOTAL WEIGHT PERCENT OFSAID TRACE ELEMENTS, SAID CONTACT DEVICE HAVING IMPROVED THERMALSTABILITY - WHEN COMPARED AGAINST CONVENTIONAL EC ALUMINUM DIVECES -WHICH RENDERS SAID CONTACT DEVICE CAPABLE OF WITHSTANDING EPEATEDCURRENT CYCLING OVER AN EXTENDED PERIOD OF TIME, WITHOUT FAILURE.
 2. Theelectrical contact device of claim 1 consisting essentially of fromabout 0.20 to about 2.00 weight percent iron, from about 0.07 to about0.25 weight percent magnesium, from about 0.02 to about 0.15 weightpercent silicon, from about 0.005 to about 0.15 weight percent copper,and from about 97.25 to about 99.72 weight percent aluminum.
 3. Theelectrical contact device of claim 2 consisting essentially of fromabout 0.05 to about 1.50 weight percent iron, from about 0.10 to about0.20 weight percent magnesium, from about 0.04 to about 0.10 weightpercent silicon, from about 0.01 to about 0.10 weight percent copper,and from about 97.90 to abot 99.35 weight percent aluminum.
 4. Theelectrical contact device of claim 1 wherein the silicon content is fromabout 0.02 to about 0.15 weight percent, the individual trace elementcontent is from about 0.0004 to about 0.04 weight percent, and the totaltrace element content is from about 0.002 to about 0.10 weight percent.5. The electrical contact device of claim 1 wherein the individual traceelement content is less than about 0.0004 percent and the total traceelement content is less than about 0.002 weight percent.
 6. Anelectrical contact device having a minimum conductivity of 57% IACScontaining substantially evenly distributed iron aluminate inclusions ina concentration produced by the presence of more than about 0.02 weightpercent iron in an alloy mass consisting essentially of from about 97.25to about 99.78 weight percent aluminum, from about 0.01 to about 0.25weight percent silicon, from about 0.07 to about 0.35 weight percentmagnesium, from about 0.0003 to about 0.20 weight percent copper, lessthan about 0.05 weight percent each of trace elements selected from thegroup consisting of vanadium, manganese, and zinc, said alloy containingno more than about 0.15 total weight percent of said trace elements,said iron aluminate inclusions having a particles size of less than10,000 angstrom units, said contact device having improved thermalstability - when compared against conventional EC aluminum devices -which renders said contact device capable of withstanding repeatedcurrent cycling over an extended period of time, without failure.
 7. Theelectrical contact device of claim 6 wherein the individual traceelement content is less than about 0.0004 weight percent, and the totaltrace element content is less than about 0.002 weight percent.
 8. Theelectrical contact device of claim 6 wherein iron is present in aconcentration of from about 0.20 to about 2.00 weight percent, magnesiumis present in a concentration from about 0.07 to about 0.25 weightpercent, silicon is present in a concentration of from about 0.02 toabout 0.15 weight percent, copper is present in a concentration of fromabout 0.005 to about 0.15 weight percent, and aluminum is present in aconcentration of from about 97.25 to about 99.72 weight percent.
 9. Theelectrical contact device of claim 8 wherein iron is present in aconcentration of from about 0.50 to about 1.50 weight percent, magnesiumis present in a concentration of from about 0.10 to about 0.20 weightpercent, silicon is present in a concentration of from about 0.04 toabout 0.10 weight percent, copper is present in a concentration of fromabout 0.01 to about 0.10 weight percent, and aluminum is present in aconcentration of from about 97.90 to about 99.35 weight percent.
 10. Theelectrical contact device of claim 6 whErein the silicon content is fromabout 0.02 to about 0.15 weight percent, the individual trace elementcontent is from about 0.0004 to about 0.04 weight percent, and the totaltrace element content is from about 0.002 to about 0.10 weight percent.11. A PROCESS FOR PREPARING AN ELECTRICAL CONTACT DEVICE HAVING AMINIMUM CONDUCTIVITY OF AT LEAST 57% IACS COMPRISING THE STEPS OF: A.ALLOYING FROM ABOUT 97.25 TO ABOUT 99.78 WEIGHT PERCENT ALIMINUM WITHMORE THAN 020 WEIGHT PERCENT IRON, FROM ABOUT 0.07 TO ABOUT 0.35 WEIGHTPERCENT MAGNESIUM, FROM ABOUT 0.01 TO ABOUT 0.25 WEIGHT PERCENT SILICON,FROM ABOUT 0.0003 TO ABOUT 0.20 WEIGHT PERCENT COPPER, AND LESS THANABOUT 0.05 WEIGHT PERCENT EACH OF TRACE ELEMENTS SELECTED FROM THE GROUPCONSISTING OF VANADIUM, MANGANESIUM AND ZINC, THE TOTAL TRACE ELEMENTCONTENT BEING NO MORE THAN ABOUT 0.15 WEIGHT PERCENT OF SAID TRACEELEMENTS, B. CASTING THE ALLOY TO FORM A CAST BAR, AND C. FORMING THEBAR WITH NO PRELIMINARY OR INTERMEDIATE ANNEALS INTO THE CONTACT DEVICE,SAID CONTACT DEVICE HAVING IMPROVED THERMAL STABILITY - WHEN COMPAREDAGAINST CONVENTIONAL EC ALUMINIUM DEVICES - WHICH ENDERS SAID CONTACTDEVICE CAPABLE OF WITHSTANDING REPEATED CURRENT CYCLING OVER AN EXTENDEDPERIOD OF TIME, WITHOUT FAILURE.
 12. The process of claim 11 includingthe step of annealing or partially annealing the contact device.
 13. Aprocess for preparing an electrical contact device having a minimumconductivity of at least 57% IACS comprising the steps of: a. Alloyingfrom about 97.25 to about 99.78 weight percent aluminum with more thanabout 0.20 weight percent iron, from about 0.07 to about 0.35 weightpercent magnesium, from about 0.01 to about 0.25 weight percent silicon,from about 0.0003 to about 0.20 weight percent copper, and less thanabout 0.05 weight percent each of trace elements selected from the groupconsisting of vanadium, manganese and zinc, the total trace elementcontent being no more than about 0.15 weight percent of said traceelements: b. Continuously casting the alloy into a continuous bar; c.Continuously rolling the bar in substantially that condition in which itwas cast to form a continuous rod; and d. Forming the rod with nopreliminary or intermediate anneals into a contact device, said contactdevice having improved thermal stability - when compared againstconventional EC aluminum devices - which renders said contact devicecapable of withstanding repeated current cycling over an extended periodof time, without failure.
 14. The process of caim 13 wherein theindividual trace element content is less than about 0.0004 weightpercent, and the total trace element content is less than about 0.002weight percent.
 15. The process of claim 13 wherein step (a) comprisesalloying from about 97.25 to about 99.72 weight percent aluminum, fromabout 0.20 to about 2.00 weight percent iron, from about 0.07 to about0.25 weight percent magnesium, from about 0.02 to about 0.15 weightpercent silicon, and from about 0.005 to about 0.15 weight percentcopper.
 16. The process of claim 15 wherein step (a) comprises alloyingfrom about 97.90 to about 99.35 weight percent aluminum, from about 0.50to about 1.50 weight percent iron, from about 0.10 to about 0.20 weightpercent magnesium, from about 0.04 to about 0.10 weight percent silicon,and from about 0.01 to about 0.10 weight percent copper.
 17. The processof claim 13 wherein the silicon content is from about 0.02 to about 0.15weight percent, the individual trace element content is from about0.0004 to about 0.04 weight percent, and the total trace element cOntentis from about 0.002 to about 0.10 weight percent.
 18. The process ofclaim 13 including the step of annealing or partially annealing thecontact device.
 19. A process for preparing an electrical contact devicehaving a minimum conductivity of at least 57% IACS and containingsubstantially evenly distributed iron aluminate inclusions having aparticle size of less than 10,000 angstrom units, comprising the stepsof: a. Alloying from about 97.25 to about 97.78 weight percent aluminumwith more than about 0.20 weight percent iron, from about 0.07 to about0.35 weight percent magnesium, from about 0.01 to about 0.25 weightpercent silicon, from about 0.0003 to about 0.20 weight percent copper,and less than about 0.05 weight percent each of trace elements selectedfrom the group consisting of vanadium, manganese and zinc, the totaltrace element content being no more than about 0.15 weight percent ofsaid trace elements; b. Continuously casting the alloy into a continuousbar; c. Continuously rolling the bar in substantially that condition inwhich it was cast to form a continuous rod; and d. Forming the rod withno preliminary or intermediate anneals into a contact device, saidcontact device having improved thermal stability - when compared againstconventional EC aluminum devices - which renders said contact devicecapable of withstanding repeated current cycling over an extended periodof time, without failure.
 20. The process of claim 19 wherein theindividual trace element content is less than about 0.0004 weightpercent, and the total trace element content is less than about 0.002weight percent.
 21. The process of claim 19 wherein step (a) comprisesalloying from about 97.25 to about 99.72 weight percent aluminum, fromabout 0.20 to about 2.00 weight percent iron, from about 0.07 to about0.25 weight percent magnesium, from about 0.02 to about 0.15 weightpercent silicon, and from about 0.005 to about 0.15 weight percentcopper.
 22. The process of claim 21, wherein step (a) comprises alloyingfrom about 97.90 to about 99.35 weight percent aluminum, from about 0.50to about 1.50 weight percent iron, from about 0.10 to about 0.20 weightpercent magnesium, from about 0.04 to about 0.10 weight percent silicon,and from about 0.01 to about 0.10 weight percent copper.
 23. The processof claim 19 wherein the silicon content is from about 0.02 to about 0.15weight percent, the individual trace element content is from about0.0004 to about 0.04 weight percent, and the total trace element is fromabout 0.002 to about 0.10 weight percent.
 24. The process of claim 19including the step of anealing or partially annealing the contactdevice.
 25. A process for preparing an electrical contact device havinga minimum conductivity of at least 57% IACS and containing substantiallyevenly distributed iron aluminate inclusions having a particle size ofless than 10,000 angstrom units comprising the steps of: a. Alloyingfrom about 97.25 to about 99.78 weight percent aluminum with more thanabout 0.20 weight percent iron, from about 0.07 to about 0.35 weightpercent magnesium, from about 0.0l to about 0.25 weight percent silicon,from about 0.0003 to about 0.20 weight percent copper, and less thanfrom about 0.0003 to about 0.20 weight percent copper, and less thanabout 0.05 weight percent each of trace elements selected from the groupconsisting of vanadium, manganese and zinc, the total trace elementcontent being no more than about 0.015 weight percent of said traceelements: b. Casting the alloy to form a cast bar; and c. Forming thebar with no preliminary or intermediate anneals into a contact device,said contact device having improved thermal stability - when comparedagainst conventional EC aluminum devices - which renders said contactdevice capable of withstanding repeated current cycling over an extendedperiod of time, without failure.
 26. The process of claim 25 includingthe step of annealing or partially annealing the contact device.